1. Field of the Invention
This invention is generally related to wireless communication systems and, more particularly, is related to a system for interfacing a wireless communication device baseband module with a wireless communication device radio frequency (RF) integrated circuit.
2. Related Art
Wireless communication systems are an integral component of the ongoing technology revolution and are evolving at an exponential rate. The wireless communication systems are generally RF communication systems. Many wireless communication systems are configured as “cellular” systems, in which the geographic area to be covered by the cellular system is divided into a plurality of “cells.” Mobile communication devices (e.g., wireless telephones, pagers, personal communications devices, and the like) in the coverage area of a cell communicate with a fixed base station within the cell. The wireless communication system is also capable of communicating with stationary communication devices, though most applications employ the mobile communication devices described above.
Typical wireless communication devices may be divided into four sections: a baseband module, an integrated analog module, a power module, and a radio frequency module. The radio frequency module is generally responsible for communicating with the fixed base stations. The radio frequency module communicates with the base station via high frequency carrier waves. The radio frequency module accepts data from the baseband module and inserts the data in the carrier wave. The radio frequency module then sends the carrier wave containing the data to the base station. The radio frequency module also removes data from incoming carrier waves and passes the data to the baseband module. The baseband module interfaces with the wireless communication device user, through a user interface, and processes incoming and outgoing data from the radio frequency module, a speaker, and a microphone.
The baseband module and the radio frequency module may include separate integrated circuits with different operating characteristics. In general, the baseband module controls the function of the components of the wireless communication module, including the components of the radio frequency module. The baseband module controls the radio frequency integrated circuit through a serial logic interface and a plurality of logic control signals. The baseband module generally reconfigures the radio frequency integrated circuit when the radio frequency integrated circuit is powered up.
Due to the different functions of the baseband module and the radio frequency module, the integrated circuits for the modules generally have different operating characteristics. The baseband integrated circuit may be a relatively low voltage (e.g. 1.8 volts), high-density contemporary complementary metal-oxide semiconductor (CMOS) processor. The baseband module processes a great deal of digital information and CMOS technology allows the implementation of a large number of digital functions. CMOS logic gates typically output logic signals referenced to the CMOS supply voltage.
Radio frequency integrated circuits generally run at relatively higher voltages, e.g. 2.7-3.0 volts. Some components within the radio frequency integrated circuit may run at different voltages than other components within the radio frequency integrated circuit. The components within the radio frequency integrated circuit generally require digital input signals at the operating voltage of the component. Therefore, the CMOS output logic signals are typically shifted to the higher voltage level of the radio frequency integrated circuit component. In order to conserve power, the radio frequency integrated circuit is typically shut down when it is not in use. Shutting down the radio frequency integrated circuit is particularly useful in time division multiple access (TDMA) wireless communication systems since there is idle time between transmitting and receiving data. When the radio frequency integrated circuit is powered up, the baseband module has to reconfigure the radio frequency integrated circuit. This results in a great deal of undesirable baseband module programming latency and excessive power consumption.
Thus, a need exists in the industry to address the problems noted above.